Preparation and Performance of Conductive Ti₄O₇ Coatings on SS316L Bipolar Plates

Proton exchange membrane water electrolysis is currently a promising technology in the hydrogen production industry. However, the high cost of titanium bipolar plates is one of the market penetration limitations. This study explores the conductivity and corrosion resistance of Ti₄O₇ by employing Ar+H₂ and Ar+He as the spraying gases for the preparation of Ti₄O₇ coatings on an SS316L substrate using atmospheric plasma spraying and low-pressure plasma spraying methods at different power levels (10, 17.5, and 25 kW). The objective is to investigate the effects of various spraying conditions on the phase composition, microstructure, corrosion resistance, and conductivity of the Ti₄O₇ coatings. The results indicate that the surfaces of the coatings obtained via low-pressure plasma spraying were confirmed to be Ti₄O₇, with a presence of Ti₃O₅ on the coating surface, while the coatings from atmospheric plasma spraying primarily comprised TiO₂. Electrochemical measurements demonstrate that the coating produced by low-pressure plasma spraying at 17.5 kW exhibited excellent corrosion resistance in a simulated anode corrosion environment of the proton exchange membrane water electrolysis cell, providing superior protection for the SS316L bipolar plates. Furthermore, the coating applied at 25 kW exhibited the highest conductivity.